package UdpServerAndClient;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpEchoServerTest {
    private DatagramSocket socket = null;
    public UdpEchoServerTest(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器启动");
        while(true){
            // 读取请求并解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            // 把读取到的信息转换成String类型
            String request = new String(requestPacket.getData(),0, requestPacket.getLength());
            // 处理数据 计算响应
            String response = process(request);
            //把响应写回到客户端
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),0,response.getBytes().length,
                            requestPacket.getSocketAddress());
            socket.send(responsePacket);

            System.out.printf("[%s:%d] req=%s, resp=%s\n",requestPacket.getAddress(),requestPacket.getPort(),request,response);
        }
    }

    private String process(String request){
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServerTest serverTest = new UdpEchoServerTest(4096);
        serverTest.start();
    }

}
